*{
    margin: 0;
    padding: 0;
  }
.clearfix::after{
    content: "";
    display: block;
    clear: both;
}
li{
    list-style: none;
}
a{
    text-decoration: none;
}
// 版心
.center{
    width: 1000px;
    margin: 0 auto;
    position: relative;
}